Thanks for good reference to RFC
I have described issue at https://github.com/kamailio/kamailio/issues/4290
On Fri, 2025-06-13 at 09:51 +0200, Aymeric Moizard via sr-users wrote:
Hi Sergey,
The extra chars are acceptable for UDP, as James reported.
Several things:
1/ the port reported in logs 60083 is not the same as your OPTIONS (just worth to say: is your error for another message? I guess not...)
2/ Your OPTIONS contains a Tag in From, but it doesn't contain a "branch" in the Via header: so your OPTIONS looks to be a mix of old rfc2543 and not compliant to rfc3261.
The Via header should contain a branch and it should start with the magic cookie: "z9hG4bK", such as:
Via: SIP/2.0/UDP 192.168.1.1:51253;branch=z9hG4bKyjoyW1QOas
Looking at sanity code, it doesn't look to be the reason for failure...
Aymeric
Antisip - http://www.antisip.com
Le jeu. 12 juin 2025, 22:38, James Browne via sr-users sr-users@lists.kamailio.org a écrit :
I read your pcap file. I thought it was invalid, but it looks valid to me, even though it's strange and I've never seen this nonsense in normal SIP traffic.
RFC3261 Section 18.3
In the case of message-oriented transports (such as UDP), if the message has a Content-Length header field, the message body is assumed to contain that many bytes. If there are additional bytes in the transport packet beyond the end of the body, they MUST be discarded.
Therefore it looks to me that any server/client should simply ignore anything after the header when the Content-Length is zero.
I don't see that error "dropping insane message" in kamailio source code, so I suppose your config file generates that. The sanity module, which Antonio mentions, would drop this message, so I guess that's what's happening in your config.
- content length - (128) - checks if the size of the body matches
with the value from the Content-Length header.
James
On Sat, 31 May 2025 at 07:27, Sergey Safarov via sr-users sr-users@lists.kamailio.org wrote:
Could you look at the attached PCAP with OPTIONS message. When OPTIONS message is received, then Kamailio generates error logs like
dropping insane message from 10.140.6.38:60083
After checking the PCAP, I see extra %x00 characters after the OPTIONS message in the same UDP frame. Example image.png
I have checked RFC3261 and do not see a definition of "x00" chars. Also in the same RFC, present a reference to the RFC2234 [1] where is described "space chars", "white space". According to RFC2223, char %x00 cannot be treated as "space" and should be treated as control (CTL) char. Also, RFC3261 does not use "CTL" chars.
Using these two RFC, I can conclude, OPTIONS in the attached PCAP breaks RFC requirements, and we can request partner fix this issue on their equipment.
Is anything else in the RFC can be used to justify that the given examples of OPTIONS messages violate RFCs?
Sergey
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[1] RFC2234 https://datatracker.ietf.org/doc/html/rfc2234
